.\"	$OpenBSD: ypbind.8,v 1.24 2014/09/08 01:27:56 schwarze Exp $
.\"	$NetBSD: ypbind.8,v 1.2 1996/02/28 01:21:00 thorpej Exp $
.\"
.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Jason R. Thorpe.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
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.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\"
.Dd $Mdocdate: September 8 2014 $
.Dt YPBIND 8
.Os
.Sh NAME
.Nm ypbind
.Nd create and maintain a binding to a YP server
.Sh SYNOPSIS
.Nm ypbind
.Op Fl insecure
.Op Fl ypset
.Op Fl ypsetme
.Sh DESCRIPTION
.Nm
finds the server for a particular YP domain and stores information about it
in a
.Dq binding file .
This binding information includes the IP address of the server associated with
that particular domain and which port the server is using.
This information is stored in the directory
.Pa /var/yp/binding
in a file named with the convention
.Pa DOMAINNAME.version .
(The YP system only supplies information on version 2.)
.Pp
When
.Nm
starts the primary domain (or gets the first request for a new domain),
it checks if a file for the domain in question exists in the directory
.Pa /etc/yp/
(i.e.,
.Pa /etc/yp/DOMAINNAME ) .
If such a file exists, it will list the hosts which
.Nm
should restrict its server search to.
Otherwise,
.Nm
assumes it will need to use broadcasts to find a valid server.
Using either of these techniques,
.Nm
will search for a server willing to serve maps for the
client's domain.
Once a binding is established,
.Nm
maintains this binding by periodically communicating with the server to which
it is bound.
If the binding is somehow lost, e.g by server reboot,
.Nm
marks the domain as unbound and attempts to re-establish the binding.
When the binding is once again successful,
.Nm
marks the domain as bound and resumes its periodic check.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl insecure
Permit binding to a
.Xr ypserv 8
on a non-reserved port.
This is needed if receiving maps from SunOS 3.x or Ultrix.
.It Fl ypset
.Xr ypset 8
may be used to change the server to which a domain is bound.
.It Fl ypsetme
.Xr ypset 8
may be used only from this machine to change the server
to which a domain is bound.
.El
.Pp
The
.Fl ypset
and
.Fl ypsetme
options are dangerous and should be avoided.
For greatest security, the use of a server list in
.Pa /etc/yp/DOMAINNAME
is recommended.
The file should contain a list of valid YP server hostnames,
with one hostname per line.
The comment character is #.
.Pp
If the directory
.Pa /var/yp/binding
exists, YP is started automatically at boot time by
.Pa /etc/rc .
.Sh FILES
.Pa /var/yp/binding/DOMAINNAME.version
- binding file for domainname
.Pa /etc/yp/DOMAINNAME
- server list for this particular domain
.Sh SEE ALSO
.Xr domainname 1 ,
.Xr ypcat 1 ,
.Xr ypmatch 1 ,
.Xr ypwhich 1 ,
.Xr yp 8 ,
.Xr yppoll 8 ,
.Xr ypserv 8 ,
.Xr ypset 8
.Pp
Once
.Nm ypbind
is running, the following pages should be reviewed in order to see how to
enable YP support for each of the following maps:
.Xr ethers 5 ,
.Xr group 5 ,
.Xr hosts 5 ,
.Xr networks 5 ,
.Xr passwd 5 ,
.Xr resolv.conf 5
.Sh AUTHORS
.An Theo de Raadt
